Organic Light Emitting Diode (OLED) is one of the hotspots in the field of panel display technology. As compared with a liquid crystal display, an OLED presents a number of advantages, such as, lower energy consumption, lower production cost, self-luminescence, a wider viewing angle, and a faster response speed. At present, in the field of display, for example, mobile phones, PDAs, digital cameras, conventional LCD displays are being replaced with OLEDs. An OLED is driven by current and its luminescence is controlled by a stable current, which is different from an LCD for which the luminance is controlled by a stable voltage. Due to processing technologies and device aging, a threshold voltage Vth of a driver transistor used for driving an OLED may be uneven, and therefore the current which passes through the OLED of each pixel varies and the luminance is not even. In this way, the display effect for the whole image is impacted.
Therefore, in an existing pixel driver circuit for driving an OLED to emit light, the impact due to threshold voltages of driver transistors will usually be eliminated. To be specific, as shown in FIG. 1A, a very typical OLED pixel driver circuit comprises: a driver transistor T2, switching transistors T1, T3, T4, T5, and T6, a storage capacitor C, and a light emitting device OLED, where the gate of the switching transistor T1 is connected to a second light emitting signal input terminal EM(n+1), its source is connected to a first reference signal terminal ELVDD, and its drain is connected to one terminal of the storage capacitor C and the source of the driver transistor T2, respectively; the gate of the driver transistor T2 is connected to the drain of the switching transistor T3 and the drain of the switching transistor T6, respectively, and its drain is connected to one terminal of the light emitting device OLED; the gate of the switching transistor T3 is connected to a second light emitting signal input terminal EM(n+1), its source is connected to the other terminal of the storage capacitor C, the drain of the switching transistor T4, and the drain of the switching transistor T5, respectively; the gate of the switching transistor T4 is connected to a first scanning signal input terminal S(n−1), and its source is connected to a second reference signal terminal Vref and the source of the switching transistor T5, respectively; the gate of the switching transistor T5 is connected to a second scanning signal input terminal S(n) and the gate of the switching transistor T6, respectively; the source of the switching transistor T6 is connected to a data voltage signal input terminal Vdata; and the other terminal of the light emitting device OLED is connected to a third reference signal terminal ELVSS.
FIG. 1B is a timing diagram of a pixel driver circuit shown in FIG. 1A. In FIG. 1B, the signal S(n−1) is a control signal that is input from an output terminal of a shift register at the (N−1)th stage in a gate driver circuit into a first scanning signal input terminal S(n−1) in a pixel driver circuit as shown in FIG. 1A. The signal S(n) is a control signal that is input from an output terminal of a shift register at the Nth stage in the gate driver circuit into the second scanning signal input terminal S(n) in the pixel driver circuit as shown in FIG. 1A. The signal EM(n) is a control signal that is input from an output terminal at the Nth stage in a light emitting driver circuit into a first light emitting signal input terminal EM(n) in the pixel driver circuit at an upper stage that is neighboring to the pixel driver circuit as shown in FIG. 1A. The signal EM(n+1) is a control signal that is input from an output terminal at the (N+1)th stage in the light emitting driver circuit into the second light emitting signal input terminal EM(n+1) in the pixel driver circuit as shown in FIG. 1A. Under the control of the three control signal terminals, i.e., the first scanning signal input terminal S(n−1), the second scanning signal input terminal S(n), and the second light emitting signal input terminal EM(n+1), the pixel driver circuit as shown in FIG. 1A may have four operation phases: the first phase in which the first scanning signal input terminal S(n−1) and the second light emitting signal input terminal EM(n+1) cause the switching transistor T1, the switching transistor T3, and the switching transistor T4 to turn on, and the pixel driver circuit accomplishes the initialization on the gate of the driver transistor T2 in addition to charging the capacitor C through the second reference signal terminal Vref and the first reference signal terminal ELVDD; the second phase in which the second scanning signal input terminal S(n) causes the switching transistor T5 and the switching transistor T6 to turn on, the data voltage is written and the threshold voltage is compensated for the driver transistor T2, and the second light emitting signal input EM(n+1) causes the switching transistor T1 and the switching transistor T3 to turn off; the third phase in which all the switching transistors turn off to prevent any noise from being generated by switching; and the fourth phase (a light emitting phase) in which the second light emitting signal input terminal EM(n+1) causes the switching transistor T1 and the switching transistor T3 to turn on, at the same time the first scanning signal input terminal S(n−1) and the second scanning signal input terminal S(n) cause rest of the switching transistors to turn off, the driver transistor T2 turns on due to the written data voltage to drive the light emitting device OLED to emit light.
From the above description, it can be determined that respective control signals are input from the gate driver circuit and the light emitting driver circuit to the first scanning signal input terminal S(n−1), the second scanning signal input terminal S(n), and the light emitting signal input terminal EM(n+1) of the pixel driver circuit at various operation phases of the pixel driver circuit, such that the pixel driver circuit is controlled to accomplish respective operations at various phases. However, in the related art, the gate driver circuit and the light emitting driver circuit for providing scanning signals and light emitting signals to various pixel driver circuits are disposed in a non-display region of a display panel independently and separately. Such a circuit design is relatively complex and not suitable for development of a display panel with narrow rims.